Hi Mauricio – I don’t have any idea off the top of my head as to why the stops wouldn’t be lined up – maybe you can attach a photo of what you’ve got? Depending on your sons height, you may look into a Noonan foot box. I have used the footbox to bring the pedals back on an Arrow and it made the process quite easy. It also raises smaller feet to help get leverage back on the ball of the foot tather than using toes.